Add setting to prevent the top layer from doing small-skin behaviour.

Actually the other way around, so we don't have another negation you have to turn on to turn off (and so the default can be false I suppose). The idea is that recently, a feature was introduced where there should be walls instead of normal skin in small hard to reach places of the model. However, this is to be excluded in most cases for all the top-layer parts exposed to air on the buildplate.

implements CURA-10829

resources/definitions/fdmprinter.def.json

@@ -1664,7 +1664,7 @@
                 "small_skin_width":
                 {
                     "label": "Small Top/Bottom Width",
-                    "description": "Small top/bottom regions are filled with walls instead of the default top/bottom pattern. This helps to avoids jerky motions.",
+                    "description": "Small top/bottom regions are filled with walls instead of the default top/bottom pattern. This helps to avoids jerky motions. Off for the topmost (air-exposed) layer by default (see 'Small Top/Bottom On Surface').",
                     "value": "skin_line_width * 2",
                     "default_value": 1,
                     "minimum_value": "0",
@@ -1675,6 +1675,17 @@
                     "settable_per_mesh": true,
                     "unit": "mm"
                 },
+                "small_skin_on_surface":
+                {
+                    "label": "Small Top/Bottom On Surface",
+                    "description": "Enable small (up to 'Small Top/Bottom Width') regions on the topmost skinned layer (exposed to air) to be filled with walls instead of the default pattern.",
+                    "value": "False",
+                    "default_value": false,
+                    "type": "bool",
+                    "enabled": "small_skin_width > 0 and top_layers > 0",
+                    "limit_to_extruder": "top_bottom_extruder_nr",
+                    "settable_per_mesh": true
+                },
                 "skin_no_small_gaps_heuristic":
                 {
                     "label": "No Skin in Z Gaps",

resources/setting_visibility/advanced.cfg

@@ -34,6 +34,8 @@ bottom_thickness
 bottom_layers
 ironing_enabled
 skin_monotonic
+small_skin_width
+small_skin_on_surface
 
 [infill]
 infill_extruder_nr